A graph turns a table full of numbers into a picture you can read at a glance.
Bar graphs are handy for comparing sizes, line graphs for changes over time, and pie charts for the share each part takes of the whole.
Everyday data comes alive this way, from a fruit survey to monthly temperatures and favorite subjects.
Here you can switch between bar, line, and pie charts and see how the same data tells a different story in each one.
Reading Bar Graphs
📊 What a Bar Graph Tells Us
①Bar height = magnitude
②Easy to compare at a glance
③Longest = largest, shortest = smallest
seegongsik.com
Various bar-chart datasets
Reading Trends with Line Graphs
📈 Line Graph Shows Change
①Going up = increase
②Going down = decrease
③Steeper slope = faster change
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seegongsik.com
Seoul monthly temperature line chart with trend analysis
Reading Ratios in Pie Charts
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seegongsik.com
Compare ratios in a favorite-subject pie chart
🍰 Pie Chart = Share of the Whole
①Whole = 100% (full circle)
②Slice size = item ratio
③Biggest slice = highest share
Summary
Bar Graph
Bar height = value
Good for comparing items
Line Graph
Steeper slope = faster change
Good for time-series trends
Pie Chart
Slice size = share of total (%)
Good for comparing parts of a whole
🎯 Key Points
①Bar graph: compare sizes (find largest/smallest)
②Line graph: see trends (increase/decrease/sudden change)
③Pie chart: share of total (%)
④Always check title and units first!
⑤Same data shows differently across graph types
Examples & Unit Review
Example 1
In a pie chart, students who like math make up 35% of a total of 200 students. How many like math?
1
Part = whole × rate = 200 × 35/100.
2
200 × 0.35 = 70, so 70 students.
▸ 70 students
To turn a pie-chart percent into a count, multiply the whole by the rate.
Example 2
In a line graph, the temperature was 10 degrees in March and 28 degrees in July. How much did it rise from March to July?
1
Change = later value - earlier value = 28 - 10.
2
28 - 10 = 18, so it rose 18 degrees.
▸ 18 degrees
In a line graph, the gap between two points is the change; a rising line means an increase.
Unit Review
In a pie chart surveying 50 people, those who like science were 20% of the total. How many like science?